JP7350191B2 - Image reading device - Google Patents

Description

This disclosure relates to an image reading device that converges transmitted light and reflected light from an object to be read (illuminated object) with a lens array arranged in an array, and reads the converged light with a sensor element array.

Conventional image reading devices (line image sensors for image reading and image input devices using the same) are equipped with a sensor that irradiates light onto an object to be read and arranges the transmitted light and reflected light from the object in an array. There is one that converges with a rod lens and reads with an optical sensor array arranged in a line (for example, see Patent Document 1). Such image reading devices are used in image reading devices such as copying machines and scanners that convert images, characters, patterns, etc. on objects to be read into electronic information.

Examples of the lens body array of the image reading device include a rod lens array of an erect equal-magnification optical system, a microlens array, and the like. Such lens body arrays are used in devices such as copying machines and scanners that are used to digitize information such as images, characters, and patterns printed on paper media. Patent Document 1 discloses that an image reading device (line image sensor) uses a rod lens array in which rod-shaped lenses are arranged in an array according to the reading width, and reads information on an object to be read illuminated by a line light source. It has been disclosed that reading is performed by imaging reflected and transmitted light included on a photosensor array placed on the opposite side of the lens array.

In addition, the rod lens array disclosed in Patent Document 1 is formed of an inorganic material such as glass, resin, etc., and has a refractive index in the radial direction so as to be an erect equal-magnification system with a predetermined aperture angle and conjugate length. By arranging these rod lenses in an array, it is possible to obtain an unbroken line-shaped image.

Furthermore, rod lens arrays are used not only as input units for facsimile machines, but also as line image sensors for back side reading built into ADFs (Automatic Document Feeders) of document scanners and copiers, as well as in commercial printing lines. Applications are also expanding to include use on production lines such as print inspection and film inspection. Although the rod lens has a fixed focus, the conjugate length (distance between focal points) of the lens can be shortened, making it a more compact image input system than a conventional optical system that reduces the image and focuses it on a small sensor surface. This is because it can form.

As the range of applications has expanded in this way, attempts have been made to improve the short conjugate length, which has contributed to the miniaturization of image sensor products, and further expand the range of applications. In order to further expand the specifications, it is necessary to improve the low tolerance (depth of field) for the positional relationship between the focal position and the object to be read (shallowness or smallness of the depth of field). In particular, in the case of in-line inspection of paper or film printing for image inspection, the object to be read may be transported at a high speed of 200 m/min or more, which causes the object to flap and change the resolution of the read image. There is a need to improve on this.

Against this background, various studies have been conducted on expanding the depth of field in line image sensors. For example, by forming an overlap limiting member between the lens elements of a lens element body and limiting the overlap of images from multiple lens elements, the depth of field can be expanded by controlling the imaging diameter of each lens element ( There are some methods that improve the depth of field (for example, Patent Document 1).

In addition, by making the peripheral part of the rod lens a non-transparent, light-absorbing layer, we can avoid a decrease in resolution due to overlapping images between rod lenses. There is a method that expands the depth of field (improves the depth of field) as a whole as a rod lens array by approaching the characteristics (for example, Patent Document 2).

Furthermore, by making the peripheral part of the rod lens a non-transmissive, light-absorbing layer, when arranging the rod lenses, gaps are provided between the lenses to ensure uniformity of the properties of the rod lens array. There is a method that improves the light amount and resolution variations between lenses that occur in the disclosed configuration, and further expands the depth of field (improves the depth of field) (for example, Patent Document 3).

Japanese Patent Application Publication No. 6-342131 Japanese Patent Application Publication No. 2000-35519 WO2013/146873

Line image sensors using rod lens arrays have a problem with ensuring depth of field. Various efforts have been made to improve the depth of field, including the performance of individual lenses. The technique disclosed in Patent Document 1 has a problem in that it is not possible to limit light that enters the limiting member at a low incident angle.

In the technology shown in Patent Document 1, a general-purpose product is used for the lens array, a light shielding member having a pitch matching the fixed lens pitch is prepared in advance as a light shielding member, and the optical path emitted from the lens is restricted. This is often an attempt to improve the depth of field. However, it is assumed that the light shielding part group is formed from one member or by combining the light shielding part groups, and originally only the arrangement of rod lenses on a flat plate was managed, but the position of each individual rod lens was not managed. An optical system is constructed by combining the lens body array 1 and a light shielding member.

Therefore, with the technology shown in Patent Document 1, it is difficult to adjust to the dimensional variations in the rod lens array, which has an actual rod lens diameter of 0.3 to 1.0 mm, such as variations in the thickness of individual rod lenses and variations in the arrangement pitch. There is a problem in that it is difficult to accurately arrange the light shielding member at a predetermined position.

Furthermore, a separate component is used to shield light from dimensional changes due to thermal expansion and contraction of the lens array due to changes in temperature and humidity, which are expected when capturing images with a sensor system using a lens configuration as shown in Patent Document 1. Since the light shielding member and the rod lens are configured as members, it is difficult to maintain a constant positional relationship between the light shielding member and the rod lens. Furthermore, it is difficult to prevent significant deterioration in image quality due to the occurrence of multiple images or image shading due to variations in the positions of the individual lenses of the lens array and the position of the light shielding member.

This disclosure was made in order to solve the above problems, and it is possible to expand the depth of field (improve the depth of field) without necessarily changing the basic characteristics of the lens body. The present invention relates to an image reading device having a structure with high accuracy that allows easy processing.

An image reading device according to a first aspect of the disclosure includes a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction. , a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction; and a sensor element array disposed between the lens body array and the sensor element array; An overlapping prevention section that prevents images of lens bodies from overlapping with each other is provided. The slit section, which is the overlap prevention section, extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and has a plurality of slit plates arranged in the main scanning direction, and the slit section has a plurality of slit plates arranged in the main scanning direction. It has a fixed leg extending toward the lens body array, the fixed leg contacts and is fixed to the fixed plate , and the surface of the slit plate is a black velvet-like surface . It is.

As described above, according to this disclosure, by restricting the optical path with a highly precisely positioned configuration, light that is incident at a low incident angle (specific light) is prevented from directly entering the sensor element 4 side. As a result, it is possible to obtain an image reading device that can expand the depth of field (improve the depth of field) while suppressing a decrease in the amount of light.

1 is a configuration diagram of an image reading device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating overlapping images of an image reading device. FIG. 3 is a diagram illustrating overlapping images of an image reading device. FIG. 3 is a configuration diagram illustrating an overlap prevention section (a member for restricting an optical path) of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing a lens body array, an overlapping prevention section, and a sensor element array of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing a lens body array and an overlap prevention unit of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing an overlap prevention section of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing an overlap prevention section of the image reading device according to the first embodiment. 3 is a diagram showing depth of field characteristics of an image reading device according to Embodiment 1 and an image reading device of a comparative example. FIG. FIG. 3 is a configuration diagram showing an overlap prevention section of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing an overlap prevention section of the image reading device according to the first embodiment. FIG. 3 is a configuration diagram showing an overlap prevention section (slit plate and specific light blocking member) of the image reading device according to the first embodiment. FIG. 7 is a configuration diagram showing an overlap prevention section (slit plate and specific light blocking member) of the image reading device according to Embodiment 2; FIG. 7 is a configuration diagram showing a lens body array of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array and an overlap prevention unit of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array and an overlap prevention unit of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array and an overlap prevention unit of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array and an overlap prevention unit of an image reading device according to a third embodiment. FIG. 3 is a diagram showing a positional shift of an image reading device. FIG. 3 is a diagram showing a positional shift of an image reading device. FIG. 3 is a diagram showing a positional shift of an image reading device. 7 is a graph showing data regarding the depth of field of the image reading device according to the third embodiment. FIG. 7 is a configuration diagram showing a lens body array of an image reading device according to a third embodiment. FIG. 7 is a configuration diagram showing a lens body array and an overlap prevention unit of an image reading device according to a third embodiment.

In the first and second embodiments, a basic explanation of the slit portion and a specific light blocking member applicable to the image reading device according to the third embodiment will be explained. In the third embodiment, fixing of the slit portion will be explained.

Embodiment 1.
Embodiment 1 will be described below using FIGS. 1 to 12. In the drawings, the same reference numerals indicate the same or corresponding parts, and detailed explanation thereof will be omitted. FIG. 1A is a cross-sectional view of the image reading device along the sub-scanning direction (transportation direction). FIG. 1(b) is a partial perspective view of the image reading device. FIG. 3A is a diagram of a single lens body (rod lens) among diagrams showing overlapping images of an image reading device. FIG. 3B is a diagram of a lens body array (rod lens array) among diagrams showing overlapping images of the image reading device.

1 to 12, a lens body array 1 has lens bodies 2 arranged in an array along the main scanning direction of an image reading device. The main scanning direction and the sub-scanning direction (conveyance direction) intersect and preferably intersect at right angles. The main scanning direction and the sub-scanning direction (conveyance direction) are orthogonal to the depth of focus direction (depth of field direction). In this application, a case is illustrated in which the optical axis direction of the lens body array 1 (lens body 2) is perpendicular to the main scanning direction and the sub-scanning direction (conveyance direction). In addition, in this application, the case where the lens body 2 is the rod lens 2, that is, the case where the lens body array 1 is the rod lens array 1, is illustrated, but the lens body array 1 may be a microlens array 1 or the like. The lens body 2 is preferably an erecting equal-magnification optical system such as a rod lens 2 or a microlens 2. In detail, in the lens body array 1, lens bodies 2 sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction. The lens body 2 is sandwiched between two fixing plates, and there is a sealing resin (fixing resin) filling the gap between them. Therefore, in the drawings, the fixing plate and the sealing resin (fixed resin) may be shown integrally in order to simplify the illustration of the fixing plate and the sealing resin (fixed resin).

1 to 12, the sensor element array 3 has sensor elements 4 (sensor ICs 4) arranged in an array along the main scanning direction, each receiving light converged by the lens body 2. The slit portion 5 is arranged between the lens body array 1 and the sensor element array 3, and prevents the images of the lens bodies 2 from overlapping with each other. The slit section 5 extends in the sub-scanning direction to partition a space, and includes a plurality of slit plates 7 arranged in the main-scanning direction. 2 and is formed in one-to-one correspondence. That is, the slit portions of the slit portion 5 are shown arranged for each optical axis of the lens body 2. Of course, it is not necessary to line up the same number of slit portions of the slit portion 5 as the pitch of the lens body 2. For example, there may be one slit portion of the slit portion 5 for every 1.5 lens bodies 2. That is, a plurality of spaces arranged in an array along the main scanning direction may be formed in correspondence with the lens bodies 2 at a ratio of 1:1.5. The slit portion 5 has a side wall plate 6, the aforementioned slit plate 7, and a specific light blocking member 8. The slit portion of the slit portion 5 is a portion surrounded by the side wall plate 6 and the slit plate 7. The slit portion 5 can be said to be an overlap prevention portion 5 that is a member for restricting the optical path. FIGS. 8A and 11A are cross-sectional views of the slit section 5 along the sub-scanning direction (conveyance direction). FIGS. 8(b) and 11 (b) are cross-sectional views of the slit portion 5 along the main scanning direction.

In FIGS. 1 to 12, an object 9 to be read (irradiated body 9, Object 9) is a sheet-like object including a document, banknote, securities, etc., a substrate, a web (textile, cloth, etc.), an image, a character, The object to be converted into electronic information, such as a pattern, is mainly present on the surface.The object to be read 9 is transported in the sub-scanning direction (transportation direction).The light source 10 emits light to the object to be read 9. Further, the lens body array 1 (lens body 2) converges reflected light or transmitted light from the reading object 9. In the present application, the light source 10 is an LED array; A case is illustrated in which the reflected light from the object to be read 9 derived from the light irradiated from the sensor substrate 11 is converged.The sensor substrate 11 is a substrate on which the sensor element array 3 (sensor elements 4) is formed. is a housing of an image reading device that holds or houses a lens body array 1 (lens body 2), a sensor substrate 11 (sensor element array 3 (sensor element 4)), a slit portion 5, and a light source 10. The sensor board 11 may be located outside the image reading device (casing 12).The object to be read 9 may be transported in the sub-scanning direction (transport direction) by the object to be read 9 itself. , the image reading device (casing 12) may be transported.

That is, the image reading device according to the first embodiment has a light source 10 that illuminates the object 9 to be read on the reading center of the rod lens array 1 and a medium image formed by the rod lens array 1. It can be said that it is a line image sensor that has a sensor element array 3 that converts the signal into an electrical signal. Here, the necessity of the slit section 5 in the image reading device (line image sensor) according to the first embodiment and the basic function of the slit section 5 will be explained in detail.

First, the necessity of the slit section 5 will be explained in detail. As explained in the problem section, the point to be improved in the line image sensor using the rod lens array 1 is ensuring the depth of field. The entire image formed by the imaging system (lens) is not formed only by the single rod lens 2. As shown in FIGS. 2 and 3, images of a plurality of rod lenses 2 are overlapped to form an entire image.

As shown in Figures 2 and 3, the main reason for the decrease in depth of field is that the lenses are arranged in an array, rather than the performance of individual lenses. The problem is that the image is not superimposed on the correct position. The degree of overlap m is a value that is 1/2 of the value obtained by dividing the diameter of the area where one rod lens 2 transfers an image at the conjugate point by the diameter of the rod lens 2. The image will be blurred if it is not superimposed at the correct position. Note that the parameter indicating the degree of overlap of images by adjacent rod lenses 2 is expressed as the degree of overlap m, which indicates the number of lenses whose images overlap in one direction from the optical axis center of the rod lens 2 of interest.

By arranging the rod lenses 2 on an array, at the conjugate point, as shown in FIG. 2 , the area where one rod lens image is formed is an area corresponding to m lenses on one side from the lens center, as shown in the degree of overlap. This means that light passing through 2 x m rod lenses 2 is used to form an image of one point, and in order to ensure resolution at the conjugate point, all lenses must have the same characteristics. It is necessary that the images be formed at the same point without any errors in placement. However, in reality, each rod lens 2 has different optical characteristics and there are assembly errors, so the image transferred by the rod lens 2 includes a slight positional shift, and the resolution at the conjugate point also differs from the rod lens 2. The optical properties are lower than when 2 is used alone.

Further, as shown on the left side of FIG. 3(a), when the positional relationship between the object to be read 9 and the sensor element array 3 is at a conjugate point, the rod lens 2 forms an erect, same-size image. . However, as shown on the right side of FIG. will be reduced. In this case, the image of each rod lens 2 is reduced on the sensor element array 3, and the image formed on the sensor element array 3 as the rod lens array 1 is It will shift little by little. Therefore, as shown on the right side of FIG. 3(b), the amount of blur increases and the resolution decreases compared to the case shown on the left side of FIG. 3(b).

In this way, the performance of the rod lens 2 alone is not the main cause of the decrease in depth of field caused by the decrease in resolution due to the position of the object to be read 9 moving away from the conjugate point (focal point). The main factors are that the rod lens 2 is used as the rod lens array 1, the difference in characteristics of adjacent rod lenses 2 defined by the degree of overlap m mentioned above, the optical axis shift due to assembly error, and the object 9 to be read is moved away from the focal position. Due to the image enlargement/reduction due to the deviation, the images formed by the individual rod lenses 2 are not superimposed at the correct position on the sensor element array 3, but are formed with a positional deviation, resulting in blurring of the image. This is due to this. Therefore, as shown in FIG. 4, it is necessary to use the slit section 5 to avoid a decrease in the depth of field.

Next, the basic functions of the slit section 5 of the image reading device according to the first embodiment will be explained in detail using FIGS. 5 to 9. The rod lens 2 shown simply in FIGS. 5 and 6 is a SLA (product name) SLA9A-1 series product manufactured by Nippon Sheet Glass, which has an aperture angle of 9°, a conjugate length of approximately 80 mm, and a lens diameter Φ of approximately 1. 0mm, overlap degree m=4.2'' was used. The state in which the slit portion 5 is arranged with respect to the rod lens array 1 is shown in FIGS. 5 and 6. The slit portion 5 shown in FIGS. 7 and 8 has a length L in the main scanning direction, a length W in the sub-scanning direction, and a length (height) in the optical axis direction. The length of the side wall plate 6 in the main scanning direction corresponds to L. The length (height) of the slit plate 7 in the optical axis direction corresponds to H. The slit plate 7 has a pitch e in the main scanning direction of about 2.0 mm, a thickness T of 0.2 mm, and a height H of 20 mm. In Embodiment 3, which will be described later, the pitch e of the slit plate 7 in the main scanning direction is approximately 1.0 mm, the thickness T of the slit plate 7 is 0.2 mm, and the height H is 10 mm.

The wall surface of the slit section 5 shown in FIGS. 5 to 8 is a black velvet-like surface to reduce the reflection of light as much as possible, so that all light incident on the surface of the slit section 5, including reflected light and scattered light, can be blocked. That is, it is preferable that the slit plate 7 and the specific light blocking member 8 have black surfaces. Moreover, it is preferable that at least the surface of the side wall plate 6 that is continuous with the slit plate 7 is a black surface. Furthermore, the black surface is preferably a black velvet-like surface. The black velvet-like surface includes a black and satin-like surface.

The slit portion 5 is fixed with a side wall plate 6 in order to maintain each slit plate 7 at a fixed distance from each other. Specifically, the slit plates 7 are each fixed by two side wall plates 6. Therefore, the side wall plate 6 can also be called a spacer 6. That is, the side wall plates 6 (spacers 6) are two pieces that extend in the main scanning direction and face each other in the sub-scanning direction that intersects with the main scanning direction. The plurality of slit plates 7 are arranged between the two side wall plates 6 along the sub-scanning direction, partition the space between the two side wall plates 6, and are the slit portions of the slit portion 5. As shown in FIGS. 6 to 8 , the side wall plate 6 is bent on the rod lens array 1 side and partially covers the end of the slit plate 7 in the sub-scanning direction, thereby limiting the light that enters the slit portion 5. It's okay. In this case, the side wall plate 6 has an L-shaped cross section along the sub-scanning direction.

The mechanical dimensions of the slit portion 5 are preferably determined for the following reasons. When the overlapping degree of the rod lenses 2 (m: 1/2 of the value obtained by dividing the area diameter where one rod lens 2 transfers an image at the conjugate point by the lens diameter Φ) and the aperture angle (θ) are as follows. Become. The pitch e between adjacent slit plates 7 formed in plurality is equal to or less than the value obtained by multiplying the degree of overlap m and the lens diameter Φ by 0.6. The length of the slit portion 5 (slit plate 7) in the optical path is greater than or equal to the value obtained by dividing the pitch e by the tangent θ when the aperture angle of the rod lens 2 is θ. In other words, the pitch e of the slit plate 7 is 0.5 x m x 0.5 x m x The height of the slit plate 7 (slit portion 5) was set to 2.0/tan (6°)≈20 mm by looking at the margin of about 2.0 mm of 1 mm and the lens aperture angle to 6°. Note that the height of the slit plate 7 (slit portion 5) is the height in the optical axis direction (reading optical axis direction). The depth of field characteristic under this condition is shown by one solid line in FIG. The other solid line is the depth of field characteristic of the image reading device to be compared.

In Embodiment 3, which will be described later, the pitch e of adjacent slit plates 7 formed in plurality is the lens diameter Φ, and the length of the slit portion 5 (slit plate 7) in the optical path is the pitch e. The value is greater than the value divided by the tangent θ when the aperture angle of 2 is θ. In other words, from the relationship of the height H of the slit plate 7 (H≧e/tan(θ)), the pitch e is set to 1 mm, the lens aperture angle is restricted to 9°, and the height of the slit plate 7 (slit part 5) is set to 1 mm. The angle was set to 1.0/tan (9°)≈10 mm.

FIG. 9 shows the depth of field characteristics of the image reading device, and the values are for a resolution of 5.681 lp/mm (line pairs/mm). In FIG. 9, a black diamond (with silt) indicates the depth of field characteristic of the image reading device according to the first embodiment. Similarly, the black circle (Normal) indicates the depth of field characteristic of the image reading device of the comparative example. Specifically, the image reading device according to the first embodiment has a slit section 5 which is an overlap prevention section 5 (with silt). On the other hand, the image reading device of the comparative example does not have the overlap prevention section 5 (Normal). Further, the vertical axis in FIG. 9 indicates MTF (Modulation Transfer Function), and the unit is %. The horizontal axis in FIG. 9 indicates the distance from the focal point (Focus plane, Focul Point) of the object 9 to be read, and the unit is mm.

As can be seen from the solid line in FIG. 9, the image reading device having the slit section 5 has a slightly lower peak resolution at the focal position, but the image reading device has a higher resolution than the object to be read in the reading optical axis direction (depth of field direction). It can be seen that there is a significant improvement with respect to the positional fluctuation of No. 9 (in FIG. 9, this can be seen by referring to the portion surrounded by the broken line on the left and the portion surrounded by the broken line on the right). The depth of field can be approximately three times larger. However, if the reflectance of the black velvet-like surface of the slit plate 7 (slit part 5) is large, the folded image will be thin due to the influence of the reflection, so the condition of the black velvet-like surface (the surface of the slit part 5) Management is required. As described above, the black velvet-like surface includes a black and satin-like surface.

In the image reading device according to the first embodiment, in order to obtain a more stable light blocking state, a specific light blocking member 8 is further provided in the slit portion 5 described above as shown in FIGS. 10 to 12. It is preferable to form. The specific light blocking member 8 is formed on the slit plate 7 to protrude in the main scanning direction, and prevents specific light incident on the sensor element 4 from entering at an angle equal to or less than the aperture angle of the rod lens 2. Specifically, the specific light blocking member 8 has a mechanical shape that prevents light (specific light) that enters the surface (wall surface) of the slit portion 5 at a low incident angle from directly entering the sensor element 4 side. be. The specific light blocking member 8 is a beam-shaped member 8 extending between one side wall plate 6 and the other side wall plate 6. The beam-shaped member 8 (specific light blocking member 8) may be discontinuous with the side wall plate 6. Preferably, the specific light blocking member 8 is a member in which the portion on the rod lens 2 side protrudes more than the portion on the sensor element 4 side, but the details will be explained in Embodiment 2.

For example, a plurality of specific light blocking members 8 as shown in FIGS. 10 to 12 are formed on the slit plate 7 along the optical axis of the rod lens 2. Specifically, it has a structure in which black beams (specific light blocking members 8) are provided at equal intervals in the reading optical axis direction (perpendicular to the reading optical axis) on the wall surface of the slit plate 7, which has been surface-treated to be black. This structure prevents low incident angle light incident on the specific light blocking member 8 (beam portion) from being reflected in the direction of the rod lens 2 and incident in the direction of the sensor element 4. By providing a certain number of specific light blocking members 8 (beam-shaped members), it is possible to block light emitted from the rod lens 2 having a diameter of about 1 mm and having a lens emission angle of 9° or less.

As shown in FIG. 12, the thickness d (length d in the optical axis direction) of the specific light blocking member 8 (beam-shaped member) is 0.1 mm, and the height a (length a in the main scanning direction or main scanning direction) is 0.1 mm. The height a) protruding in the scanning direction is 0.1 mm, and the pitch f (interval f) is 0.55 mm. The thickness T of the slit plate 7 is 0.2 mm. The height a (length a in the main scanning direction or the height a protruding in the main scanning direction) of the specific light blocking member 8 (beam-shaped member) and the pitch f are the aperture angle θ of the rod lens 2. depends on. That is, it is preferable that the height a and the pitch f satisfy the relationship "a/f≧tan(θ)".

The specific light blocking member 8 (beam-shaped member) makes it possible to obtain stable characteristics without being easily influenced by the condition of the surface (wall surface) of the slit portion 5. Even when the specific light blocking member 8 (beam-shaped member) is provided, the peak resolution at the focal position is slightly reduced, but it is greatly improved against positional fluctuations of the reading target section 9 in the reading optical axis direction. do. The depth of field can be approximately three times larger.

Embodiment 2.
Embodiment 2 will be described using FIG. 13. Description of parts common to Embodiment 1 may be omitted. Further, in the drawings, the same reference numerals indicate the same or corresponding parts, and detailed explanation thereof will be omitted. In the image reading device according to the second embodiment, as shown in FIG. ). In other words, the height a (length a in the main scanning direction or height a protruding in the main scanning direction) of the specific light blocking member 8 (beam-shaped member) is higher than the rod lens on the sensor element 4 side. It can be said that it is lower than the second side. Preferably, the shape of the specific light blocking member 8 in a virtual cross section where the main scanning direction and the optical axis direction intersect is a right triangle. The hypotenuse of this right triangle does not have to be a straight line in the strict sense, but may be an arc. Note that the specific light blocking member 8 of the image reading device according to the first embodiment has a rectangular shape in a virtual cross section where the main scanning direction and the optical axis direction intersect.

By using the specific light blocking member 8 of the image reading device according to the second embodiment, since the hypotenuse of the right triangle that is the outer shape of the specific light blocking member 8 is inclined with respect to the optical axis direction, specific light can be blocked. Reflection of light toward the sensor element 4 by the blocking member 8 can be further suppressed. Therefore, in the image reading device according to the second embodiment, the thickness d (length d in the optical axis direction) of the specific light blocking member 8 (beam-shaped member), the pitch f (Pitch f, interval f), and the specific light blocking member 8 (beam-shaped member) The entire length t of the slit plate 7 including the blocking member 8 in the main scanning direction, and the height a of the specific light blocking member 8 (beam-shaped member) (length a in the main scanning direction or protruding in the main scanning direction) When the height a) is the same as that of the image reading device according to the first embodiment, the height a of the specific light blocking member 8 (beam-shaped member) is shorter on the sensor element 4 side, so that the image reading device can be more stable. An image reading device with improved depth of field and stable image quality can be obtained. Note that the image reading device according to the second embodiment also preferably satisfies the relationship “a/f≧tan(θ)”.

As described above, according to the image reading apparatus according to the first and second embodiments, by restricting the optical path, light (specific light) that enters at a low incident angle is prevented from directly entering the sensor element 4 side. By doing so, it is possible to expand the depth of field (improve the depth of field) while suppressing a decrease in the amount of light.

On the other hand, in improving the depth of field using a single rod lens as shown in Patent Document 2, the following problems remain. That is, as shown in Patent Document 3, there is a problem in that it is difficult to ensure uniformity of resolution and brightness with respect to changes in the position of the object to be read in the depth direction. Furthermore, in Patent Document 2, when a long line sensor is formed, the brightness distribution changes due to changes in the environment (in particular, the relative position of the lens and sensor array due to differences in thermal expansion due to temperature fluctuations). Regardless of the shading correction performed, unevenness in illuminance and sensitivity degrades image quality. In addition, when improving the depth of field with a rod lens alone, the area of the part that functions as a lens must be made smaller in order to ensure the independence of the lens, which reduces the amount of light that contributes to image formation and distorts the image. It becomes dark, or it is necessary to prepare lighting that is brighter than necessary, making it difficult to configure a faster reading system.

The technique shown in Patent Document 3 can ensure the uniformity of resolution and brightness that accompanies changes in the medium position as in Patent Document 2. However, with the technology shown in Patent Document 3, compared to Patent Document 2, the area of the part that functions as a lens has to be made smaller, which reduces the amount of light that contributes to image formation and makes the image darker or unnecessary. It is necessary to prepare even brighter lighting, making it difficult to construct a faster reading system. In addition, with the technology shown in Patent Document 2 and Patent Document 3, it is necessary to change the basic characteristics of the lens, so various operating distances (distance from the lens end to the reading medium) required for inspection applications etc. It is difficult to respond to

Unlike Patent Documents 1, 2, and 3, the image reading devices according to Embodiments 1 and 2 can expand the depth of field (increase the depth of field) without necessarily changing the basic characteristics of the lens body. The present invention relates to an image reading device that can be easily improved.

Embodiment 3.
Embodiment 3 will be described using FIGS. 14 to 26. Although illustrations of the side wall plate 6 (spacer 6) and specific light blocking member 8 described in the image reading apparatus according to the first and second embodiments are omitted, they can be applied to the image reading apparatus according to the third embodiment. Other than the side wall plate 6 (spacer 6) and the specific light blocking member 8, the image reading device according to the third embodiment and the image reading devices according to the first and second embodiments have the same basic configuration as an image reading device. Therefore, the explanation will be omitted.

In the image reading device according to the third embodiment, the structures shown in FIGS. 14, 15, and 16, the structures shown in FIGS. 17 and 18, and the structures shown in FIGS. 19 and 20 have a light shielding wall ( In order to provide the slit plates 7), this positioning structure corresponds one-to-one to the fixed plates 13, which are both side plates forming the lens body array 1, with the lens bodies 2. These have a highly precisely positioned configuration, and by restricting the optical path, it prevents light that enters at a low angle of incidence (specific light) from directly entering the sensor element 4 side, thereby suppressing a decrease in light intensity. However, the depth of field can be expanded (improved).

In FIGS. 14 to 20, the fixing plate 13 sandwiches the lens bodies 2 between two sheets extending along the main scanning direction, and arranges the lens bodies 2 in an array along the main scanning direction to form a lens body array. 1. As described in the first embodiment, a sealing resin (fixing resin) is filled between the lens body 2 and the fixing plate 13. The slit section 5, which is an overlap prevention section, extends in the sub-scanning direction to partition a space, and includes a plurality of slit plates 7 arranged in the main scanning direction, and the slit plates 7 are fixed to the fixed plate 13. . The plurality of slit plates 7 extend in the sub-scanning direction to partition spaces, and are arranged in the main-scanning direction, so that the plurality of spaces arranged in an array along the main-scanning direction correspond one-to-one with the lens body 2 . The figure shows what is formed. The slit portion 5 has a fixed leg 14 extending toward the lens body array 1 side, and the fixed leg 14 is in contact with the fixed plate 13. The fixed plate 13 has a fitting part 15 that fits into the fixed leg 14.

As shown in FIG. 14, FIG. 15, and FIG. ) are formed along the grooves 16. Alternatively, as shown in FIGS. 17 and 18, the fitting portion 15 is a plurality of holes 17 into which the fixed legs 14 are inserted along the optical axis of the lens array 1. Furthermore, as shown in FIGS. 19 and 20, the two fixing plates 13 have a line-symmetrical shape in the main scanning direction, extend in a zigzag shape along the main scanning direction, and are separated from each other by a distance in the sub-scanning direction. The fitting portions 15 may be grooves 18 that are shorter than the above. In this case, as shown in the figure, the lens body 2 is fixed between the grooves 18 of the two fixing plates 13 . It can be said that the fitting portions 15 have a structure in which a plurality of fitting portions 15 are formed along the main scanning direction. The material of the fixing plate 13 shown in FIGS. 19 and 20 will be described later.

FIG. 14(A) is a diagram of the lens body array 1 viewed from the optical axis direction. FIG. 14(B) is a diagram of the lens body array 1 viewed from the sub-scanning direction. FIG. 14 shows the lens body array 1 before the slit plate 7 is attached. The unit of dimension is mm. FIG. 15 is a diagram showing a state in which a plurality of slit plates 7 are fixed to the lens body array 1 shown in FIG. 14. FIG. 16(A) is a diagram of the lens array 1 and the slit plate 7 viewed from the optical axis direction. FIG. 16(B) is a diagram of the lens array 1 and the slit plate 7 viewed from the sub-scanning direction.

The structure shown in FIGS. 14, 15, and 16 is an extension of the section of the lens body 2 adjacent to the fixing plate 13, which is a side plate for sandwiching and holding the lens body array 1, as a positioning structure for the lens body array 1 . A groove 16 centered on the lens body 2 and parallel to the cylindrical direction (optical axis direction) is provided, and by fitting with the fixed leg 14, the positioning and uprightness of the slit portion 5 (slit plate 7) are ensured. There is.

FIG. 17(A) is a diagram of the lens body array 1 viewed from the optical axis direction. FIG. 17(B) is a diagram of the lens array 1 viewed from the sub-scanning direction. In FIG. 17(B), the hole 17 (fitting portion 15) is shown in a dotted line because it is in a transparent state. FIG. 17 shows the lens body array 1 before the slit plate 7 is attached. FIG. 18 is a diagram showing a state in which the fixing leg 14 is about to be inserted (fitted) into the hole 17 (fitting portion 15) in order to fix the plurality of slit plates 7 to the lens body array 1 shown in FIG. 17. .

The structure shown in FIGS. 17 and 18 is a positioning structure for the lens body array 1, and the center is located at the extension of the section of the lens body 2 adjacent to the fixing plate 13, which is a side plate for sandwiching and holding the lens body array 1. A hole 17 having a depth in the cylindrical direction (optical axis direction) of the lens body 2 is provided, and by fitting with the fixed leg 14, the positioning and uprightness of the slit portion 5 (slit plate 7) are ensured. . The fixed leg 14 at this time has a shape that can be inserted into the hole 17.

FIG. 19(A) is a diagram of the lens body array 1 viewed from the optical axis direction. FIG. 19(B) is a diagram of the lens body array 1 viewed from the sub-scanning direction. FIG. 19 shows the lens body array 1 before the slit plate 7 is attached. FIG. 20 is a diagram showing a state in which the fixing leg 14 is about to be inserted (fitted) into the groove 18 (fitting portion 15) in order to fix the plurality of slit plates 7 to the lens body array 1 shown in FIG. 19. .

The structure shown in FIGS. 19 and 20 is a positioning structure for the lens body array 1, and the center is located at the extension of the section of the lens body 2 adjacent to the fixing plate 13, which is a side plate for sandwiching and holding the lens body array 1. A groove 18 parallel to the cylindrical direction (optical axis direction) of the lens body 2 is provided. The groove 18 is a part where the fixed plate 13, which is the two side plates, has a line-symmetrical shape in the main scanning direction, extends in a zigzag shape along the main scanning direction, and has a shorter distance in the sub-scanning direction than other parts. be. In this way, by fitting the groove 18 and the fixed leg 14, the positioning and uprightness of the slit portion 5 (slit plate 7) are ensured.

Up to now, the case has been explained in which the fixed legs 14 are formed on the slit plate 7, but the fixed legs 14 may also be formed on the side wall plate 6 (spacer 6) described in Embodiments 1 and 2. good. When the fixed legs 14 are formed on the side wall plate 6, the slit plate 7 is fixed to the fixed plate 13 via the side wall plate 6. Of course, the fixed legs 14 may be formed on both the slit plate 7 and the side wall plate 6. In other words, the fixed legs 14 only need to be formed on at least one of the slit plate 7 or the side wall plate 6. Further, since the fixed leg 14 is also a part of the slit portion 5, the surface may be a black surface. In particular, at least the surface of the fixed leg 14 that is continuous with the slit plate is black. For example, the black surface is a black velvety surface.

Since the image reading device according to the third embodiment has the structures shown in FIGS. 14, 15, and 16, the structure shown in FIGS. 17 and 18, and the structure shown in FIGS. 19 and 20, the slit portion 5 (slit By fixing the fixing leg 14 formed on at least one of the plate 7 or the side wall plate 6 to the fixing plate 13, the slit plate 7 can be installed with high positional accuracy of the slit plate 7 of the slit part 5. .

FIG. 21, FIG. 22, and FIG. 23 are diagrams showing the positional deviation of the image reading device. In FIG. 21, the horizontal axis represents the pitch of two lens bodies, and the vertical axis represents the frequency. FIG. 22 is a diagram of the lens body array 1 viewed from the optical axis direction. The unit of dimension is mm. FIG. 23 is a diagram of the lens array 1 and the slit plate 7 viewed from the optical axis direction. As shown in FIGS. 21 and 22, the pitch variation of the lens bodies 2 in the lens body array 1 is about ±5 μm as a distribution of the individual average value, and even within the same lens body array 1, the pitch variation of the lens bodies 2 is about ±5 μm. The distribution is about ±10 μm. In the 7 groups of slit plates formed with a single pitch, the accumulation of pitch deviations creates a portion where the optical path separation between the individual lens bodies 2 cannot be performed correctly, as shown in FIG. It may become impossible to obtain a uniform image over the entire length.

In order to prevent a uniform image from being obtained over the entire length of the sensor element array 3, in processing the side plate (fixing plate 13) of the lens body array 1, the number of lens bodies 2 in the total reading length is reduced. The dimensions are measured, the average pitch is calculated, and the influence of lens pitch variations between the two lens bodies in one lens body array is removed. After determining the starting point, a group of fitting portions 15 (grooves 16, holes 17, and grooves 18) are formed at equal intervals at an average pitch of the lens body array 2. By forming the group of fitting portions 15 in this way, it is possible to prevent the center position of the slit plate 7 from shifting from between the lens bodies 2 by an amount greater than the variation in the arrangement of the lens bodies 2.

In order to prevent variations in the arrangement of the lens bodies 2, the fitting portion 15 may be misaligned by a maximum of ±0.03 mm with respect to the ideal arrangement with a thickness of 0.1 mm (the slit plates 7 overlap each lens body 2 by 0.05 mm). (Groove 16, hole 17, groove 18) can be formed. If more precision is desired, the position of the lens body 2 may be recognized using an imaging device such as a camera when forming the fitting portion 15 (groove 16, hole 17, groove 18), and the fitting portion 15 may be aligned.

Further, in the image reading device according to the third embodiment, the slit plate 7 is made thinner while ensuring strength, and in order to increase the aperture ratio of the lens body 2, a 0.1 mm thick stainless steel plate is made into a 4.0 mm wide stainless steel plate. , the height of the slit plate 7 (height in the optical axis direction) is 10 mm, and the length of the fitting part 15 is 5 mm. Specifically, since the material is stainless steel, the stainless steel surface is sandblasted to give it a satin finish, and then black plating with low light reflection is applied. Furthermore, the formation of the slit plate 7 in the lens body array 1 is achieved by fitting the slit plate 7 (fixed leg 14) into the fitting part 15, which is a hole or groove on the side surface of the lens body array 1, and forming the fitting part (fitting part). It is fixed by applying adhesive.

By doing this, in the image reading device according to the third embodiment, the volume occupied by the slit plate 7 portion can be reduced (the width direction dimension of the slit plate 7 portion can be reduced), and the conventional sensor module mechanism is significantly changed. It can be assembled without any hassle. Furthermore, the slit plates 7 can stand on their own even without the side wall plate 6 (spacer 6), which is a structure that connects the slit plates 7 (the holding part of the slit plates 7 in the main scanning direction of the lens array 2). , it is also easy to eliminate the influence of proximity reflection of the emitted light.

FIG. 24 is a graph showing data regarding the depth of field of the image reading device according to the third embodiment. The horizontal axis shows the focal position, and the vertical axis shows the resolution (MTF). The broken line is the data of the lens body array 1 without the slit plate 7, and the solid line is the data of the lens body array 1 with the slit plate 7, that is, the data of the image reading device according to the third embodiment. Three samples are plotted for each. Specifically, the depth of field in the configuration of the image reading device according to the third embodiment is shown by three solid lines in FIG. Although the resolution at the peak is slightly lower than the depth of field of the conventional lens body 2 shown by the three broken lines in FIG. It can be seen that the depth of field can be approximately three times larger.

Up to now, the width of the slit plate 7 has been set to 4.0 mm, which is almost the same as the width of the lens body array 1, but the width of the slit plate 7 only needs to be the same width as the diameter of the lens body 2 in the light-shielding part, and A similar effect can be obtained by changing it according to the mechanism. A stainless steel plate may be used as the base material of the slit plate 7 to ensure strength, but the material of the slit plate 7 is a resin that is easy to process and create an attachment shape, and the surface is treated with low reflection treatment. You may go. Furthermore, the thickness of the slit plate 7 was set to 0.1 mm due to material availability, but with the condition that the shape stability of the slit plate 7 can be ensured, the thinner the slit plate 7, the smaller the restricted area of light emitted from the lens body array 1. This makes it possible to reduce the reduction in brightness of the optical system.

As shown in FIGS. 17 and 18, when the fitting portion 15 of the image reading device according to the third embodiment is a hole 17, a hole 17 is formed on both sides of the side plate of the lens body array 1, and at a tangential position between adjacent lens bodies 2. Seventeen rows of holes with a predetermined diameter are formed. By fitting seven groups of slit plates whose surfaces were blackened and subjected to low reflection treatment into these 17 rows of holes, seven groups of slit plates having a one-to-one positional relationship with the lens body 2 were formed. Since the lens bodies 2 of the lens body array 1 are arranged perpendicularly to the lens surface, the 17 rows of holes formed in the side plate (fixing plate 13) of the lens body array 1 must be formed in a direction perpendicular to the lens surface. Bye.

This time, for the thickness of the slit plate 7 of 0.2 mm, 17 rows of holes with a diameter of 0.2 mm and a depth of 5 mm were formed on both sides of the lens light exit surface side, and aligned and fixed between the adjacent lens bodies 2. By doing so, the lens body 2 and the slit plate 7 were placed in a predetermined position on a one-to-one basis. At this time, the diameter of the hole 17 for fixing the slit plate 7 is sufficient as long as it remains thick enough to maintain strength with respect to the thickness of the side plate (fixing plate 13) of the lens array 1 . For example, when the thickness of the side plate (fixed plate 13) is approximately 1.9 mm, the diameter is set to 0.2 mmΦ. It is possible to increase the size to approximately 1/2 or less of the side plate (fixing plate 13) of the lens body array 1 .

In this way, the fitting portion 15 of the image reading device according to the third embodiment is able to position the slit portion 5 (slit plate 7 group) by processing the fixing plate 13, which is the side plate of the lens array 1. The structure allows for installation. These structures can provide a mechanism for improving the depth of field without increasing the cross-sectional area occupied by the lens system itself and without significantly changing the mechanical parts of conventional image reading devices.

Note that in the lens body array 1, the lens bodies 2 are arranged in an array along the main scanning direction, and the lens bodies 2 are sandwiched between two fixed plates 13 extending along the main scanning direction. However, the fixing plate 13 may be formed outside the lens array 1 instead of forming the lens array 1 . However, even with this structure, it goes without saying that the lens body 2 can be expressed as being sandwiched between two fixing plates 13. That is, the lens body array 1 may be integrated with the fixed plate 13 or may be a separate body (separate component).

When the lens body array 1 and the fixing plate 13 are integrated, the lens body array 1 needs to be processed in order to provide the fitting part 15, which requires time and processing precision, and the manufacturing cost is relatively low. There is a possibility that it will be higher. Therefore, we considered the positioning and attachment of the slit portion 5 (slit plate 7 group) in the following configuration as a structure that takes into consideration the case where the lens body array 1 and the fixing plate 13 are separate bodies. This will be explained using FIGS. 25 and 26. In FIGS. 25 and 26, the fixing plate 13 is a rubber plate 13 that is separate from the lens body array 1. The groove 16 is formed in the rubber plate 13 (fixed plate 13) along the optical axis of the lens body array 1 (the optical axis direction coincides with the cylindrical direction or the depth of focus direction (depth of field direction)). It is what was done. The adhesive layer 19 is a layer of adhesive such as double-sided tape.

FIG. 25(A) is a diagram of the lens body array 1 viewed from the optical axis direction. FIG. 25(B) is a diagram of the lens body array 1 viewed from the sub-scanning direction. FIG. 25 shows the lens body array 1 before the slit plate 7 is attached. The unit of dimension is mm. FIG. 26 is a diagram showing a state in which the fixing leg 14 is about to be inserted (fitted) into the groove 16 (fitting portion 15) in order to fix the plurality of slit plates 7 to the lens body array 1 shown in FIG. 25. . In FIG. 26, in order to make the positional relationship easier to understand, the ends of one fixing plate 13 (rubber plate 13), the adhesive layer 19, and the side plate of the lens body 2 are connected by the adhesive layer 19. 13) and the side plate of the lens body 2 are shown hypothetically separated from each other before being bonded.

A fitting portion 15 of the image reading device according to the third embodiment shown in FIGS. 25 and 26 is formed on a fixing plate 13 that is a rubber plate 13 separate from the lens body array 1. Explain how to assemble it. First, apart from the lens body array 1, a thin rubber plate 13 is formed by molding, on which the necessary number of grooves 16 having the same width as the slit plate 7 are arranged in parallel at a pitch that is the statistically minimum value of the arrangement pitch of the lens bodies 2. . Next, the adjacent lens bodies 2 are bonded together using an adhesive layer 19 so that the grooves 16 of the rubber plate 13 are located between them, and the opposite surface of the lens body array 1 is similarly treated.

By making the pitch of the grooves 16 of the rubber plate 13 smaller than the pitch between the lens bodies 2, the lens body array 1 and the rubber plate 13 are fixed by aligning the grooves 16 at one end of the lens body array 1. When attaching the lens body array 1 and the rubber plate 13, the rubber plate 13 is stretched so that the position of the groove 16 matches the position of the lens body 2, and the rubber plate 13 is pasted together. The position of the body 2 and the position of the groove 16 are adjusted. By performing this operation on the opposite side, processing can be performed so that the slit plate 7 can be placed and fixed at a predetermined position between the lens bodies 2. Of course, if the thickness of the rubber plate 13 can be selected appropriately, the holes 17 shown in FIGS. 17 and 18 may be formed in the rubber plate 13 instead of the grooves 16, or the two rubber plates 13 The fitting portion 15 may be a groove 18 having a line-symmetrical shape, extending in a zigzag shape along the main scanning direction, and having a shorter distance than other portions in the sub-scanning direction.

By inserting the slit portion 5 (slit plate 7 or side wall plate 6) into the fitting portions 15 formed on these rubber plates 13, the slit plate 7 can be positioned and held. At this time, since the grooved rubber plate 13 can be processed by rubber molding, if a length change of about 5% in the total length can be secured as extensibility after molding, the position of the lens body 2 and the fitting part 15 can be adjusted. It is possible to align the positions of the parts, and since it can be produced as a separate part, there is a cost advantage.

Up to now, a configuration suitable for attaching the slit portion 5 (slit plate 7) to the lens body array 1 in post-processing has been described, but the image reading device according to the third embodiment is not limited to this. do not have. Further, different positioning of the slit portion 5 (slit plate 7) will be explained. The lens body array 1 is manufactured by closely arranging the lens bodies 2 in parallel on an FRP (Fiber Reinforced Plastics) flat plate, and sandwiching and adhesively fixing the lens bodies 2 between two FRP plates. When the fixing plate 13 is formed integrally with the lens body array 1, the FRP plate corresponds to the fixing plate 13. Because variations in the lens system, distortion and inclination of the rods occur during arrangement, and because the reference for lens arrangement is only at both ends of the arrangement of the lens array, it is difficult to grasp the position of each lens body 2 in the subsequent process. was difficult.

Therefore, by providing a structure in advance for arranging the lens body 2 on the side plate on which the lens body 2 is placed, and furthermore using an FRP board with a structure indicating the position between the paired lenses on the opposite side, the lens The structure may be such that the position between the lens bodies 2 is indicated on the body array 1 itself. What is suitable for this purpose is that the two fixed plates 13 (FRP plates) shown in FIGS. 19 and 20 have a line-symmetrical shape in the main scanning direction, extend in a zigzag shape along the main scanning direction, and extend in the sub-scanning direction. The groove 18 whose distance is shorter than other parts is the fitting part 15 . The lens body 2 is fixed between the grooves 18.

Specifically, the lens body 2 fixing side of the FRP plate has a triangular cross section on the side plate lens holding side at a pitch that matches the diameter of the lens body 2 element wire diameter, and the protrusion row to be held is attached to the lens body 2 side surface. A structure (for example, a triangular concave shape) indicating the lens body 2 arrangement position is provided on the opposite surface of the FRP board at a position shifted by 1/2 pitch from the lens fixing protrusion row. A lens body array 1 is formed by these two side plates. By doing this, as shown in FIG. 19, the position of the lens body 2 is determined with respect to the side plate regardless of the lens diameter or arrangement distortion, and the position of the lens body 2 is determined with respect to the side plate, as shown in FIG. 20. The position of the wall (slit plate 7) can be determined and installed.

When the fixing plate 13 shown in FIGS. 19 and 20 is formed from an FRP board, it may be formed all at once when the FRP board is molded, or it may be formed afterward or a separate part may be bonded to the base FRP board. It's okay. By making the fixing plate 13 have such a structure, it becomes possible to improve the lens position accuracy and install and fix the light shielding plate in the recessed part of the side plate, and it is possible to improve the workability while improving the optical characteristics. Become.

As described above, the image reading device according to the third embodiment provides a structure for positioning the lens body 2 on the side plate (fixing plate 13) for holding the lens body 2 in the lens body array 1, and also It can be said that a positioning structure corresponding to the positioning structure of the lens body 2 is formed on the opposite surface. In addition, in the lens body array 1 having a structure in which the lens bodies 2 arranged in a row are fixed by two side plates (fixing plates 13), the lens position is fixed to the lens fixing surface of the side plates (fixing plates 13). It has a fixed structure arranged at a lens pitch so as to be in contact with the side surface of the lens body 2, and the lens body 2 and the lens body are arranged on the outer surface of the side plate (fixed plate 13). It can be said that a structure for fixing the slit plate 7 is arranged between the side plates 2 and 2, and the lens body 2 is bonded to this side plate.

Further, in the image reading device according to the third embodiment, the lens body array 1 is a thin plate having a structure for positioning and holding a slit plate 7, which is a light shielding member, on one side, and lens bodies arranged in an array. The lens body is provided with seven groups of slit plates which are sandwiched and bonded together and arranged at predetermined positions relative to the two groups of lens bodies. Further, the thin plate (fixing plate 13) having a structure for positioning and holding the slit plate 7, which is a light shielding member, may be formed of a stretchable material. The portions for positioning and holding the slit plate 7 may be arranged at a pitch equal to or less than the minimum lens pitch of the lens body array 2.

Further, in the image reading device according to the third embodiment, as a method for forming the lens body array 1, a flexible thin plate (rubber plate 13) is fixed after aligning the fitting part 15, which is the installation structure of the lens body 2 and the slit plate 7, at the end or center of the lens body array 1, and while stretching the thin plate, attach other parts in order. The positional accuracy of the lens and the light shielding member installation structure may be ensured over the entire length.

As described above, the image reading apparatus according to the first to third embodiments can increase the height of the slit portion 5 (slit body 7) by fitting (inserting) the fixed leg 14 into the fitting portion 15 formed on the fixed plate 13. Since accurate positioning is easy, an image reading device with stable depth of field improvement and stable image quality can be obtained.

Further, in the image reading apparatus according to the first to third embodiments, the light path is restricted by the slit portion 5 or the fixing plate 13, so that the light (specific light) incident at a low incident angle is directly incident on the sensor element 4 side. This can be prevented. Therefore, an image reading device with stable depth of field improvement and stable image quality can be obtained without necessarily changing the basic characteristics of the lens body.

1 Lens body array (rod lens array)
2 Lens body (rod lens)
3 Sensor element array 4 Sensor element (sensor IC)
5 Slit part (overlap prevention part)
6 Side wall plate (spacer)
7 Slit plate 8 Specific light blocking member (beam-shaped member)
9 Object to be read (irradiated object, Object)
10 Light source 11 Sensor board 12 Housing 13 Fixing plate (rubber plate)
14 Fixed leg 15 Fitting part 16 Groove 17 Hole 18 Groove 19 Adhesive layer.

Claims (23)

a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit portion serving as the overlap prevention portion extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and includes a plurality of slit plates arranged in the main scanning direction,
The slit portion has a fixed leg extending toward the lens body array, and the fixed leg contacts and is fixed to the fixed plate ,
The surface of the slit plate is a black velvet-like surface . The plurality of slit plates extend in the sub-scanning direction to partition spaces, and are arranged in the main-scanning direction, and the plurality of spaces arranged in an array along the main-scanning direction are connected to the lens body. The image reading device according to claim 1, which is formed in one-to-one correspondence. The image reading device according to claim 1 , wherein the fixing plate has a fitting portion that fits with the fixing leg. 3. The fitting portion is a plurality of grooves formed along the optical axis of the lens body array, or a plurality of holes into which the fixed legs are inserted along the optical axis of the lens body array. The image reading device described in . The two fixing plates have a line-symmetrical shape in the main scanning direction, extend in a zigzag shape along the main scanning direction, and each has a groove that is shorter than the other portions in the sub-scanning direction. 4. The image reading apparatus according to claim 3, wherein the image reading apparatus is a part of the image reading apparatus. The image reading device according to claim 5, wherein the lens body is fixed between the grooves of the two fixing plates. 7. The image reading device according to claim 1, wherein the fixing plate is a rubber plate separate from the lens array. a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit portion serving as the overlap prevention portion extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and includes a plurality of slit plates arranged in the main scanning direction,
the slit plate is fixed to the fixed plate,
The fixing plate is a rubber plate separate from the lens body array ,
The surface of the slit plate is a black velvet-like surface . The slit portion is formed on the slit plate to protrude in the main scanning direction, and further includes a specific light blocking member that prevents specific light incident at an angle equal to or less than an aperture angle of the lens body from entering the sensor element. The image reading device according to any one of claims 1 to 8. The slit portion further includes two side wall plates extending in the main scanning direction and facing each other in the sub-scanning direction,
10. The image reading device according to claim 9, wherein the specific light blocking member is a beam-shaped member extending between one of the side wall plates and the other side wall plate. a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit section, which is the overlap prevention section, extends in the main scanning direction and is arranged between two side wall plates that face each other in a sub-scanning direction that intersects the main scanning direction, and a slit section that extends in the sub-scanning direction and connects the two side wall plates facing each other in a sub-scanning direction that intersects the main scanning direction. a plurality of slit plates arranged in the main scanning direction, dividing a space between the side wall plates;
the slit plate is fixed to the fixed plate,
The slit portion is formed on the slit plate to protrude in the main scanning direction, and prevents specific light incident at an angle equal to or less than the aperture angle of the lens body from entering the sensor element. and the other side wall plate, further comprising a specific light blocking member that is a beam- shaped member ,
The surface of the slit plate is a black velvet-like surface . 12. The image reading device according to claim 10, wherein at least one of the slit plate and the side wall plate has a fixed leg extending toward the lens body array. 13. The plurality of slit plates are arranged between the two side wall plates along the sub-scanning direction, and partition a space between the two side wall plates. The image reading device described. 14. The image reading device according to claim 9, wherein the specific light blocking member is a member in which a portion closer to the lens body protrudes than a portion closer to the sensor element. a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit portion serving as the overlap prevention portion extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and includes a plurality of slit plates arranged in the main scanning direction,
the slit plate is fixed to the fixed plate,
The slit portion is formed on the slit plate to protrude in the main scanning direction, and is provided on the sensor element side to prevent specific light incident at an angle equal to or less than the aperture angle of the lens body from entering the sensor element. a specific light blocking member, which is a member whose part on the lens body side is more protruding than the other parts ;
The surface of the slit plate is a black velvet-like surface . 16. The image reading device according to claim 9, wherein a plurality of the specific light blocking members are formed on the slit plate along the optical axis of the lens body array. 17. The image reading device according to claim 16, wherein an interval e between adjacent slit plates formed in plurality is equal to or less than a value obtained by multiplying the degree of overlap m by 0.6 and the lens diameter Φ of the lens body. a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit portion serving as the overlap prevention portion extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and includes a plurality of slit plates arranged in the main scanning direction,
the slit plate is fixed to the fixed plate,
The slit portion is formed on the slit plate to protrude in the main scanning direction, and is configured to prevent specific light incident on the sensor element from entering the sensor element at an angle equal to or less than the aperture angle of the lens body. A plurality of specific light blocking members are formed on the slit plate along the optical axis,
The distance e between adjacent slit plates formed in plurality is equal to or less than the value obtained by multiplying the degree of overlap m by 0.6 and the lens diameter Φ of the lens body,
The surface of the slit plate is a black velvet-like surface . The image reading device according to claim 17 or 18, wherein the length of the slit portion in the optical path is greater than or equal to the value obtained by dividing the interval e by a tangent θ when the aperture angle is θ. The image reading device according to claim 9 , wherein the specific light blocking member has a black surface. 14. The image reading device according to claim 10, wherein at least a surface of the side wall plate that is continuous with the slit plate is black. The image reading device according to claim 20 or 21, wherein the black surface is a black velvet-like surface. a lens body array in which lens bodies sandwiched between two fixed plates extending along the main scanning direction are arranged in an array along the main scanning direction;
a sensor element array in which sensor elements each receiving light converged by the lens body are arranged in an array along the main scanning direction;
an overlapping prevention section disposed between the lens body array and the sensor element array to prevent images of the lens bodies from overlapping;
The slit portion serving as the overlap prevention portion extends in a sub-scanning direction intersecting the main scanning direction to partition a space, and includes a plurality of slit plates arranged in the main scanning direction,
the slit plate is fixed to the fixed plate,
The slit portion is formed on the slit plate to protrude in the main scanning direction, and includes a specific light blocking member that prevents specific light incident at an angle equal to or less than an aperture angle of the lens body from entering the sensor element. ,
The slit plate and the specific light blocking member have a black surface,
The black surface is a black velvet-like surface.

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